#define NULL 0

char*
mystrstr(string, substring)
register char* string;	/* String to search. */
char* substring;		/* Substring to try to find in string. */
{
	register char* a, * b;

	/* First scan quickly through the two strings looking for a
	 * single-character match.  When it's found, then compare the
	 * rest of the substring.
	 */

	b = substring;
	if (*b == 0) {
		return string;
	}
	for (; *string != 0; string += 1) {
		if (*string != *b) {
			continue;
		}
		a = string;
		while (1) {
			if (*b == 0) {
				return string;
			}
			if (*a++ != *b++) {
				break;
			}
		}
		b = substring;
	}
	return NULL;
}
